/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */
package org.apache.hc.client5.http.impl.async;

import java.io.Closeable;
import java.io.IOException;
import java.util.List;
import java.util.Set;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Function;

import org.apache.hc.client5.http.HttpRoute;
import org.apache.hc.client5.http.async.AsyncExecCallback;
import org.apache.hc.client5.http.async.AsyncExecChain;
import org.apache.hc.client5.http.async.AsyncExecRuntime;
import org.apache.hc.client5.http.auth.AuthSchemeFactory;
import org.apache.hc.client5.http.auth.CredentialsProvider;
import org.apache.hc.client5.http.config.Configurable;
import org.apache.hc.client5.http.config.RequestConfig;
import org.apache.hc.client5.http.cookie.CookieSpecFactory;
import org.apache.hc.client5.http.cookie.CookieStore;
import org.apache.hc.client5.http.impl.ExecSupport;
import org.apache.hc.client5.http.protocol.HttpClientContext;
import org.apache.hc.client5.http.routing.RoutingSupport;
import org.apache.hc.core5.concurrent.Cancellable;
import org.apache.hc.core5.concurrent.ComplexFuture;
import org.apache.hc.core5.concurrent.DefaultThreadFactory;
import org.apache.hc.core5.concurrent.FutureCallback;
import org.apache.hc.core5.http.EntityDetails;
import org.apache.hc.core5.http.HttpException;
import org.apache.hc.core5.http.HttpHost;
import org.apache.hc.core5.http.HttpRequest;
import org.apache.hc.core5.http.HttpResponse;
import org.apache.hc.core5.http.HttpStatus;
import org.apache.hc.core5.http.config.Lookup;
import org.apache.hc.core5.http.nio.AsyncDataConsumer;
import org.apache.hc.core5.http.nio.AsyncEntityProducer;
import org.apache.hc.core5.http.nio.AsyncPushConsumer;
import org.apache.hc.core5.http.nio.AsyncRequestProducer;
import org.apache.hc.core5.http.nio.AsyncResponseConsumer;
import org.apache.hc.core5.http.nio.DataStreamChannel;
import org.apache.hc.core5.http.nio.HandlerFactory;
import org.apache.hc.core5.http.protocol.HttpContext;
import org.apache.hc.core5.http.support.BasicRequestBuilder;
import org.apache.hc.core5.io.CloseMode;
import org.apache.hc.core5.io.ModalCloseable;
import org.apache.hc.core5.net.URIAuthority;
import org.apache.hc.core5.reactor.DefaultConnectingIOReactor;
import org.apache.hc.core5.util.TimeValue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

abstract class InternalAbstractHttpAsyncClient extends AbstractHttpAsyncClientBase {

    private final static ThreadFactory SCHEDULER_THREAD_FACTORY = new DefaultThreadFactory("Scheduled-executor", true);

    private static final Logger LOG = LoggerFactory.getLogger(InternalAbstractHttpAsyncClient.class);

    private final AsyncExecChainElement execChain;
    private final Lookup<CookieSpecFactory> cookieSpecRegistry;
    private final Lookup<AuthSchemeFactory> authSchemeRegistry;
    private final CookieStore cookieStore;
    private final CredentialsProvider credentialsProvider;
    private final Function<HttpContext, HttpClientContext> contextAdaptor;
    private final RequestConfig defaultConfig;
    private final ConcurrentLinkedQueue<Closeable> closeables;
    private final ScheduledExecutorService scheduledExecutorService;
    private final AsyncExecChain.Scheduler scheduler;

    InternalAbstractHttpAsyncClient(
            final DefaultConnectingIOReactor ioReactor,
            final AsyncPushConsumerRegistry pushConsumerRegistry,
            final ThreadFactory threadFactory,
            final AsyncExecChainElement execChain,
            final Lookup<CookieSpecFactory> cookieSpecRegistry,
            final Lookup<AuthSchemeFactory> authSchemeRegistry,
            final CookieStore cookieStore,
            final CredentialsProvider credentialsProvider,
            final Function<HttpContext, HttpClientContext> contextAdaptor,
            final RequestConfig defaultConfig,
            final List<Closeable> closeables) {
        super(ioReactor, pushConsumerRegistry, threadFactory);
        this.execChain = execChain;
        this.cookieSpecRegistry = cookieSpecRegistry;
        this.authSchemeRegistry = authSchemeRegistry;
        this.cookieStore = cookieStore;
        this.credentialsProvider = credentialsProvider;
        this.contextAdaptor = contextAdaptor;
        this.defaultConfig = defaultConfig;
        this.closeables = closeables != null ? new ConcurrentLinkedQueue<>(closeables) : null;
        this.scheduledExecutorService = Executors.newSingleThreadScheduledExecutor(SCHEDULER_THREAD_FACTORY);
        this.scheduler = new AsyncExecChain.Scheduler() {

            @Override
            public void scheduleExecution(
                    final HttpRequest request,
                    final AsyncEntityProducer entityProducer,
                    final AsyncExecChain.Scope scope,
                    final AsyncExecCallback asyncExecCallback,
                    final TimeValue delay) {
                executeScheduled(request, entityProducer, scope, execChain::execute, asyncExecCallback, delay);
            }

            @Override
            public void scheduleExecution(
                    final HttpRequest request,
                    final AsyncEntityProducer entityProducer,
                    final AsyncExecChain.Scope scope,
                    final AsyncExecChain chain,
                    final AsyncExecCallback asyncExecCallback,
                    final TimeValue delay) {
                executeScheduled(request, entityProducer, scope, chain, asyncExecCallback, delay);
            }
        };

    }

    @Override
    void internalClose(final CloseMode closeMode) {
        if (this.closeables != null) {
            Closeable closeable;
            while ((closeable = this.closeables.poll()) != null) {
                try {
                    if (closeable instanceof ModalCloseable) {
                        ((ModalCloseable) closeable).close(closeMode);
                    } else {
                        closeable.close();
                    }
                } catch (final IOException ex) {
                    LOG.error(ex.getMessage(), ex);
                }
            }
        }
        final List<Runnable> runnables = this.scheduledExecutorService.shutdownNow();
        for (final Runnable runnable: runnables) {
            if (runnable instanceof Cancellable) {
                ((Cancellable) runnable).cancel();
            }
        }
    }

    private void setupContext(final HttpClientContext context) {
        if (context.getAuthSchemeRegistry() == null) {
            context.setAuthSchemeRegistry(authSchemeRegistry);
        }
        if (context.getCookieSpecRegistry() == null) {
            context.setCookieSpecRegistry(cookieSpecRegistry);
        }
        if (context.getCookieStore() == null) {
            context.setCookieStore(cookieStore);
        }
        if (context.getCredentialsProvider() == null) {
            context.setCredentialsProvider(credentialsProvider);
        }
        if (context.getRequestConfig() == null) {
            context.setRequestConfig(defaultConfig);
        }
    }

    abstract AsyncExecRuntime createAsyncExecRuntime(HandlerFactory<AsyncPushConsumer> pushHandlerFactory);

    abstract HttpRoute determineRoute(HttpHost httpHost, HttpRequest request, HttpClientContext clientContext) throws HttpException;

    @Override
    protected <T> Future<T> doExecute(
            final HttpHost target,
            final AsyncRequestProducer requestProducer,
            final AsyncResponseConsumer<T> responseConsumer,
            final HandlerFactory<AsyncPushConsumer> pushHandlerFactory,
            final HttpContext context,
            final FutureCallback<T> callback) {
        final ComplexFuture<T> future = new ComplexFuture<>(callback);
        try {
            if (!isRunning()) {
                throw new CancellationException("Request execution cancelled");
            }
            final HttpClientContext clientContext = contextAdaptor.apply(context);
            requestProducer.sendRequest((request, entityDetails, c) -> {

                RequestConfig requestConfig = null;
                if (request instanceof Configurable) {
                    requestConfig = ((Configurable) request).getConfig();
                }
                if (requestConfig != null) {
                    clientContext.setRequestConfig(requestConfig);
                }

                setupContext(clientContext);

                final HttpHost resolvedTarget = target != null ? target : RoutingSupport.determineHost(request);
                if (resolvedTarget != null) {
                    if (request.getScheme() == null) {
                        request.setScheme(resolvedTarget.getSchemeName());
                    }
                    if (request.getAuthority() == null) {
                        request.setAuthority(new URIAuthority(resolvedTarget));
                    }
                }

                final HttpRoute route = determineRoute(
                        resolvedTarget,
                        request,
                        clientContext);
                final String exchangeId = ExecSupport.getNextExchangeId();
                clientContext.setExchangeId(exchangeId);
                if (LOG.isDebugEnabled()) {
                    LOG.debug("{} preparing request execution", exchangeId);
                }
                final AsyncExecRuntime execRuntime = createAsyncExecRuntime(pushHandlerFactory);

                final AsyncExecChain.Scope scope = new AsyncExecChain.Scope(exchangeId, route, request, future,
                        clientContext, execRuntime, scheduler, new AtomicInteger(1));
                final AtomicBoolean outputTerminated = new AtomicBoolean(false);
                executeImmediate(
                        BasicRequestBuilder.copy(request).build(),
                        entityDetails != null ? new AsyncEntityProducer() {

                            @Override
                            public void releaseResources() {
                                requestProducer.releaseResources();
                            }

                            @Override
                            public void failed(final Exception cause) {
                                requestProducer.failed(cause);
                            }

                            @Override
                            public boolean isRepeatable() {
                                return requestProducer.isRepeatable();
                            }

                            @Override
                            public long getContentLength() {
                                return entityDetails.getContentLength();
                            }

                            @Override
                            public String getContentType() {
                                return entityDetails.getContentType();
                            }

                            @Override
                            public String getContentEncoding() {
                                return entityDetails.getContentEncoding();
                            }

                            @Override
                            public boolean isChunked() {
                                return entityDetails.isChunked();
                            }

                            @Override
                            public Set<String> getTrailerNames() {
                                return entityDetails.getTrailerNames();
                            }

                            @Override
                            public int available() {
                                return requestProducer.available();
                            }

                            @Override
                            public void produce(final DataStreamChannel channel) throws IOException {
                                if (outputTerminated.get()) {
                                    channel.endStream();
                                    return;
                                }
                                requestProducer.produce(channel);
                            }

                        } : null,
                        scope,
                        execChain::execute,
                        new AsyncExecCallback() {

                            @Override
                            public AsyncDataConsumer handleResponse(
                                    final HttpResponse response,
                                    final EntityDetails entityDetails) throws HttpException, IOException {
                                if (response.getCode() >= HttpStatus.SC_CLIENT_ERROR) {
                                    outputTerminated.set(true);
                                    requestProducer.releaseResources();
                                }
                                responseConsumer.consumeResponse(response, entityDetails, c,
                                        new FutureCallback<T>() {

                                            @Override
                                            public void completed(final T result) {
                                                future.completed(result);
                                            }

                                            @Override
                                            public void failed(final Exception ex) {
                                                future.failed(ex);
                                            }

                                            @Override
                                            public void cancelled() {
                                                future.cancel();
                                            }

                                        });
                                return entityDetails != null ? responseConsumer : null;
                            }

                            @Override
                            public void handleInformationResponse(
                                    final HttpResponse response) throws HttpException, IOException {
                                responseConsumer.informationResponse(response, c);
                            }

                            @Override
                            public void completed() {
                                if (LOG.isDebugEnabled()) {
                                    LOG.debug("{} message exchange successfully completed", exchangeId);
                                }
                                try {
                                    execRuntime.releaseEndpoint();
                                } finally {
                                    responseConsumer.releaseResources();
                                    requestProducer.releaseResources();
                                }
                            }

                            @Override
                            public void failed(final Exception cause) {
                                if (LOG.isDebugEnabled()) {
                                    LOG.debug("{} request failed: {}", exchangeId, cause.getMessage());
                                }
                                try {
                                    execRuntime.discardEndpoint();
                                    responseConsumer.failed(cause);
                                } finally {
                                    try {
                                        future.failed(cause);
                                    } finally {
                                        responseConsumer.releaseResources();
                                        requestProducer.releaseResources();
                                    }
                                }
                            }

                        });
            }, clientContext);
        } catch (final HttpException | IOException | IllegalStateException ex) {
            future.failed(ex);
        }
        return future;
    }

    void executeImmediate(
            final HttpRequest request,
            final AsyncEntityProducer entityProducer,
            final AsyncExecChain.Scope scope,
            final AsyncExecChain chain,
            final AsyncExecCallback asyncExecCallback) throws HttpException, IOException {
        chain.proceed(request, entityProducer, scope, asyncExecCallback);
    }

    void executeScheduled(
            final HttpRequest request,
            final AsyncEntityProducer entityProducer,
            final AsyncExecChain.Scope scope,
            final AsyncExecChain chain,
            final AsyncExecCallback asyncExecCallback,
            final TimeValue delay) {
        final ScheduledRequestExecution scheduledTask = new ScheduledRequestExecution(
                request, entityProducer, scope, chain, asyncExecCallback, delay);
        if (TimeValue.isPositive(delay)) {
            scheduledExecutorService.schedule(scheduledTask, delay.getDuration(), delay.getTimeUnit());
        } else {
            scheduledExecutorService.execute(scheduledTask);
        }
    }

    class ScheduledRequestExecution implements Runnable, Cancellable {

        final HttpRequest request;
        final AsyncEntityProducer entityProducer;
        final AsyncExecChain.Scope scope;
        final AsyncExecChain chain;
        final AsyncExecCallback asyncExecCallback;
        final TimeValue delay;

        ScheduledRequestExecution(final HttpRequest request,
                                  final AsyncEntityProducer entityProducer,
                                  final AsyncExecChain.Scope scope,
                                  final AsyncExecChain chain,
                                  final AsyncExecCallback asyncExecCallback,
                                  final TimeValue delay) {
            this.request = request;
            this.entityProducer = entityProducer;
            this.scope = scope;
            this.chain = chain;
            this.asyncExecCallback = asyncExecCallback;
            this.delay = delay;
        }

        @Override
        public void run() {
            try {
                chain.proceed(request, entityProducer, scope, asyncExecCallback);
            } catch (final Exception ex) {
                asyncExecCallback.failed(ex);
            }
        }

        @Override
        public boolean cancel() {
            asyncExecCallback.failed(new CancellationException("Request execution cancelled"));
            return true;
        }

    }

}
